In recent years, a cyclic olefin resin is noted as a transparent heat-resistant resin used in optical materials (for example, see Non-Patent Document 1), and for example, cyclic olefin resins obtained by subjecting a tetracyclodecene compound or a norbornene compound to metathesis polymerization and hydrogenating the resulting polymer (for example, see Patent Documents 1 to 4), addition polymers of ethylene and a norbornene compound, or ethylene and a cyclodecene compound (for example, see Patent Document 5), and addition polymers of a norbornene compound (for example, see Patent Documents 6 to 9) are proposed.
Polymers of the norbornene compound have excellent characteristics as a transparent material for optical applications as being excellent in transparency, heat resistance and moldability and having high Abbe number.
On the other hand, in recent years, materials having high refractive index are demanded according to the tread of lightweight and size reduction of mobile devices. However, the polymers of the norbornene compound have the problem that refractive index is low.
As a method of achieving high refractive index of a transparent heat-resistant resin, a method of introducing an aromatic ring and a sulfur atom in a molecular structure is known, and as a material having an aromatic ring introduced therein, a material having a fluorene skeleton introduced therein is proposed (for example, see Patent Document 10 or Non-Patent Document 2). Further, a thiourethane resin having a sulfur atom introduced therein is proposed (for example, see Patent Document 11).
Patent Document 1: JP 3050196
Patent Document 2: JP-A-60-026024
Patent Document 3: JP-A-01-132625
Patent Document 4: JP 3087421
Patent Document 5: JP-A-61-292601
Patent Document 6: JP-A-04-063807
Patent Document 7: JP 3534127
Patent Document 8: JP-A-09-508649
Patent Document 9: JP-A-11-505880
Patent Document 10: JP-A-11-060706
Patent Document 11: JP-B-06-005323
Non-Patent Document 1: Polyfile, September number, p. 36-43 (2004)
Non-Patent Document 2: NIKKEI ELECTRONICS, p. 79-85 (2004.9.13)